Firefighters made guarded progress today in battling the roughly 2,000-acre blaze, working their way along the edges of the fire line and trying to hold the fire's large perimeter while allowing the blaze to burn away at its center, officials said.

Firefighters edged along the high-temperature crown fire focusing on keeping the blaze away from residences and safeguarding property and historical areas. More moderate winds allowed firefighters to strategize containment as they defensively stationed along its border, keeping the fire 50 yards away from the city's only high school.

"It's such a hot fire, and it's so intense, that for a while, you really couldn't get any firefighters in the area," said Sgt. Don Atkinson of the El Dorado County Sheriff's Department. "We're concentrating right now on trying to save homes and keep homes from burning. The fire's pretty much consuming trees and vegetation in the burnt area, and we'd rather it do that than consume homes."

As the winds died down, the smoke settled upon the fire area, making visibility terrible and preventing water drops, which were finally restarted midafternoon today.

Linda Prien of Petaluma has a second home in the Mount Olympia area within the fire zone. She and her three boys, ages 16, 14 and 12, were at the beach today when the evacuation came. They were not allowed to return home.

Prien tried to sneak in to the fire zone with a Mountain Democrat reporter today but was asked by officials to get out of the car because she wasn't a journalist. As Prien sat on the corner waiting for the reporter to return, she was certain that her home had burned.

"I was sitting on the corner waiting for them to come get me, and I knew it was burned," she said. "I thought, 'It's time to start over.' "

But the reporter returned with good news: The house was fine. They had taken a photo of the house to show her. The bad news was that more than three-quarters of the houses in the neighborhood had burned.

Two of the nine choppers are up in the air about 2:30 p.m. this afternoon for the first time today after thick smoke kept them grounded this morning, said Sgt. Don Atkinson of the El Dorado Sheriff's Department. The choppers are equipped with buckets to begin dropping water again but will also be doing observation to determine the current containment level and the fire line area, Atkinson said.

"What they're working on right now is the north end of the [fire] area, between the fire line and Camp Richardson," Atkinson said. "They're working the northern fire line right now, which goes basically due west from the high school along the edge of Gardner Mountain.... That's where the residential property is ... and other historical spots they're trying to keep from becoming endangered."

Fire Capt. Brian Eagan of the California Department of Forestry stood on a steep ridgeline where his crew managed to save a neighborhood of million-dollar homes and pointed to the crest where a stand of trees was burned like matchsticks.

"You can see where this whole ridge was slicked off," he said, referencing a term used to describe so-called crown fires, where flames leap from tree to tree. "It's nothing more than standing logs now."

With crown fires, he said, the flames travel extremely fast with temperatures sometimes reaching as high as 1,500 degrees, he said. Unlike with grass fires, the heat can be sustained for as long as an hour, making it very diffcult for firefighters to battle, he said.

"When it gets into the trees, all we can do is back off," said Eagan, a 23 year veteran of the state fire department. "There's nothing we can do."

Several conditions helped prime the fire, including the dry weather, the winds and housing situated deep in the wilderness.

"You could have all the resources in the world and you couldn't have stopped it," Eagan said. "When you put homes into this kind of setting, where wind and fires occur -- not just here; it's statewide -- our focus goes from fighting fires to protecting homes."

Eagan also said homeowners still failed to realize the importance of clearing out brush and deadwood around their homes.

The blaze got within about 50 yards of the city's only high school, South Tahoe High School, where dozens of firefighters and about eight engines were in defensive positions, said Sgt. Don Atkinson of the El Dorado Sheriff's Department.

"They've got some backfires going to burn out the underbrush, so if the fire reaches the school again, it won't be so supercharged," Atkinson said. "They've probably got eight or 10 engines here around the school, so they're ready if something happens."

Jeff Nieves, the Eldorado County sheriff, said 173 structures had suffered total or major loss, nine suffered moderate loss and 17 suffered minor loss.

Officials are still investigating the cause but believe the fire was human-caused simply because there wasn't any lightning in the area. The fire is not burning in treetops anymore, and winds are calmer, both of which are very good developments.

But winds are now starting to pick up.

"The next few hours are going to be very telling for us. If it gets up in the treetops again, it will be a significant challenge for all our resources."

Although planes may have been up in the air for observation earlier today, none are currently up dropping water, said Sgt. Don Atkinson of the El Dorado County Sheriff's Department.

"I don't believe they're actively dropping water; they're staged right now. But because no residences are currently threatened at the moment, they're [letting] the center burn, and they're saving their water resources for if the fire starts to break out of that containment line," Atkinson said.

From his office in Reno, Gary Zunino could see a brown column of smoke rising more than 50 miles to the southwest -- evidence of the kind of wildfire thought to be the most destructive to wilderness and the most frustrating to firefighters.

In the trade, they're known as "crown fires.'' They leap from treetop to treetop, dancing through a canopy well beyond the reach of ground crews. Even aerial drops are often ineffective; crown fires burn so hot that water and fire retardants can evaporate before they do much good.

"They're virtually impossible to stop until they run out of fuel,'' said Zunino, director of the University of Nevada's Fire Science Academy.

"The big challenge is to keep the fire from getting up there in the first place.''

The U.S. Forest Service describes the fire that has destroyed more than 220 structures in the South Lake Tahoe area as a crown fire. It's an especially treacherous fire to fight because it's in rugged terrain, produces cascading volumes of blinding smoke and is consuming tall, tinder-dry trees that have been weakened by drought or killed by insects.

Evergreens like the pines and firs in the area can be saturated with pitch and "literally explode,'' Zunino said.

The incident command post is at the base of Heavenly Mountain Ski resort. By midday Monday, some of the first California Department of Corrections and Rehabilitation Departments fire crews were relieved after about 16 hours on the fire lines.

"We have several hundred members of fire attack crews on the scene," said Ken Cesler, a correctional lieutenant. "It is hot, heavy, nasty work. It went on the lines at about 5 p.m. yesterday," he said, noting that most of the crews were still working the fire Monday afternoon.

James White, 41, is a Compton resident serving a burglary sentence at the Washington Ridge Fire Camp in Nevada County. He serves as a second-in-command on one of the fire crews supervised by California Department of Forestry Captains.

"We just did 15 hours. We worked through the night with head lamps and wearing shrouds."

White was part of a 15-member crew that did back-burning to prevent the fire from reaching the local high school.

"We were saving the school, the high school, we burned right behind the football field," White said. "We succeeded, the school was saved. The line was in the back and is all black and is all burned."